1. Field of the Invention
The present invention relates to a powder coating composition which is employed for coating an automobile, a building material or a metal product.
2. Description of the Background Art
Acrylic resin powder coating material is watched with interest in view of the excellent appearance of a coating film as formed, weather resistance, solvent resistance, flexibility and the like. Powder coating material which is applied to clear coating or the like is known as an acrylic resin powder coating material. For example, each of Japanese Patent Publication Nos. 53-15089 (1978), 58-4947 (1983) and 58-25388 (1983) discloses acrylic resin powder coating material prepared from acrylic resin containing glycidyl groups, which is heat-cured after coating.
Such acrylic resin powder coating material is baked at a temperature of 160.degree. to 180.degree. C. after coating, while it is desired that a coating film can be formed by baking the coating material at a lower temperature of 130.degree. to 160.degree. C., for example, in consideration of productivity and energy saving. When conventional acrylic resin powder coating material is baked at such a low temperature, however, the appearance of the coating film is deteriorated with reduction in weather resistance and blocking resistance. While it may be possible to add a curing catalyst to the coating material for facilitating curing at a low temperature, storage stability is deteriorated in this case.